Oil seal for use in a rotary piston internal combustion engine

ABSTRACT

An oil seal is provided for use in a rotary piston internal combustion engine. The oil seal has an annular groove provided on the annular sliding face which is formed into a lip face having a lip angle Alpha to an adjacent inside wall face of a side housing of the engine and which includes a contacting face formed on the radial inner peripheral side thereof and disposed in frictional contact with the inside wall face in such a position that the distance between both the radial inner peripheral faces of the groove and the oil seal is within the maximum width of a contacting face which may perform the normal operation of the oil seal.

nited States Patent Sakamalti et al.

OIlL SEAL FOR USE IN A ROTARY PISTON INTERNAL COMBUSTION ENGINE Inventors: Hiroshi Sakamaki, Tochigi; Hiroshi Ozeki, Hiroshima, both of Japan Assignee: Nippon Piston Ring Co., Ltd.,

Tokyo, Japan Filed: Apr. 7, 1972 Appl. No.: 241,939

lForeign Application Priority Data Apr. 8, 1971 Japan 46-25835[U] U.S. Cl. 418/142 Int. CL... FOllc 19/00, F04c 15/00, F04c 27/00 Field of Search 418/142, 91; 277/201, 202,

References Cited UNITED STATES PATENTS Osakada et a1. 418/142 3,400,939 9/1968 Jones 418/142 FOREIGN PATENTS OR APPLICATIONS 1,016,540 1'/1966 Great Britain 418/142 1,803,533 5/1970 Germany 418/142 Primary ExaminerCarlton Croyle Assistant ExaminerJohn J. Vrablik Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak [5 7] ABSTRACT An oil seal is provided for use in a rotary piston internal combustion engine. The oil seal has an annular groove provided on the annular sliding face which is formed into a lip face having a lip angle a to an adjacent inside wall face of a side housing of the engine and which includes a contacting face formed on the radial inner peripheral side thereof and disposed in frictional contact with the inside wall face in such a position that the distance between both the radial inner peripheral faces of the groove and the oil seal is within the maximum width of a contacting face which may perform the normal operation of the oil seal.

1 Claim, 7 Drawing Figures SHEET 1 Of 2 FIG I PRIOR ART SWQQEWZSS Wmmsm mm SHEET 3 BF 2 OIL SEAL FOR USE IN A ROTARY PISTON INTERNAL CUMBUSTIION ENGINE This invention relates to an oil seal for use in a rotary piston internal combustion engine and more particularly relates to improvements in such an oil seal which is disposed in an annular groove provided in a rotor side face for sealing between the rotor side face and an adjacent inside wall face of a side housing of the engine and which provides a further improved scaling function therebetween.

In general, for the purpose of lubricating and cooling the rotary piston internal combustion engine, the lubrieating oil is caused to flow through or along elements of the engine by various means such as a pump, and this oil is, as a matter of course, caused to flow between the rotor side face and the inside wall face. Therefore, the function required for the oil seal is to prevent the leakage of the oil into the combustion chamber in order to prevent an increase of the lubricating oil consumption and the accumulation of carbon slag during operation of the engine, and to form a proper lubricating oil film on the inside wall face of the side housing to facilitate the easy sliding of the oil seal. For this purpose, as shown in FIG. 3, an annular sliding face 6a of a conventional oil seal 6 is formed into a lip face having a lip angle a to the adjacent inside wall face since the oil seal rotates about its central axis while said axis is revolving about the longitudinal axis of the engine, at any given time one side of said seal 6 is moving downwardly with respect to wall 2 while a diametrically opposite portion is moving upwardly, with reference to FIG. 3. Thus, when seal 6 moves downwardly with respect to the wall 2, it scrapes oil form the wall face 21. When it moves upwardly, it floats on the oil on the wall surface due to the angle a. This alternately scraping/floating action combined with the planetary motion of the seal serves to force oil toward the central axis of the engine. This is commonly referred to as the oil take in action.

However, such an oil seal 6 having lip angle a at the sliding face thereof has a great disadvantage in that it is impossible to maintain such an oil take-in effect for a long time. More particularly, contact area between the oil seal 6 and the wall face 21, shown as A in FIG. 3, increases due to wear of the seal material. Once this dimension exceeds a finite limit, the lowering of the contact pressure between the seal 6 and the wall surface 21 allows an excessive amount of oil to be introduced thereby increasing the consumption of lubricating oil and the accumulation of carbon slag to the detriment of the normal operation of the engine.

The present invention, therefore, contemplates the elimination of the aforesaid disadvantages of the conventional oil seal of a rotary piston internal combustion engine and provides an improved oil seal with a simple structure which has an improved sealing function between the rotor side face and the adjacent inside wall face of the side housing.

According to one aspect of the present invention, there is provided an oil seal for a rotary piston internal combustion engine which oil seal has an annular groove provided on the sliding face thereof in such a position that the distance between the radial inner peripheral faces of the groove and the oil seal is equal to or less than the radial dimension of the contact area between seal 6 and wall surface 21 which allows excessive oil consumption.

These and other objects, features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a vertical longitudinal sectional view of a prior art rotary piston internal combustion engine;

FIG. 2 is a longitudinal sectional view taken along the line II-II in FIG. 1;

FIG. 3 is a partially enlarged longitudinal sectional view of a prior art rotary piston internal combustion engine using a conventional oil seal;

FIGS. 4A and 4B are enlarged longitudinal sectional views of the oil seal according to the present invention;

FIG. 5 is a front view of the oil seal shown in FIG. 4A; and

FIG. 6 is a partially enlarged longitudinal sectional view of the rotary piston internal combustion engine using the oil seal according to the present invention wherein the contacting face of the oil seal has reached its maximum extent.

Reference is now made to the drawings, which show one embodiment of the present invention.

Reference numeral 1 illustrates the center housing of a conventional rotary piston internal combustion engine, 2 is a side housing, 3 is an eccentric shaft bridged between the side housings 2,2, 4 is a rotor supported by the eccentric shaft 3 in such a manner that the rotor 4 is eccentrically rotated while sliding within the inside wall faces of the center housing and the side housing, 5 represents an annular oil seal groove recessed on the thrust face of the rotor 4, 6 is an oil seal mounted in the oil seal groove 5, the oil seal 6 includes an O-ring 8 and a spring 7 provided at the axial inner face of the oil seal 6 so as to urge the oil seal 6 onto the adjacent inside wall face 21 of the side housing.

In FIGS. 4A, 4B, 5 and 6, the oil seal of the present invention has an annular groove 63 provided on an annular sliding face 61 which is formed into a lip face 61a having a lip angle a to the adjacent inside wall face 21 in such a position that the distance between both the radial inner peripheral faces of the groove 63 and the oil seal is within the maximum width of a contacting face A which may perform normal operation of the oil seal in the engine.

Generally, in an automobile having the rotary piston internal combustion engine, the maximum width of the contacting face A is 0.8 mm from the inner peripheral face 62 of the oil seal; accordingly the annular groove 63 is provided at or near the limit of 0.8 mm from the inner peripheral face 62. Further, it is more preferable when some contacting width C is initially provided on the lip face 61a as shown in FIG. 43.

By using the above described oil seal according to the present invention in the rotary piston internal combustion engine, the oil pressure P represented by the arrow mark for leaking the oil outward of the oil seal 60 is decreased under the action of the annular groove 63 when the contacting face A is progressively worn and reaches the maximum width as shown in FIG. 6, that is, when the contacting width between the contacting face A and the adjacent inside wall face 21 becomes 0.8 mm in such an automobile operation as mentioned above, so that the leakage of the oil is remarkably prevented, and moreover since the oil is always existing in the groove 63, the lip face 61a is remarkably protected from the frictional wear itself. Thus, the oil tightness of the oil seal is sufficiently maintained so as to prevent an increase in the lubricating oil consumption and accumulation of the carbon slag.

Though the sectional forms of the annular groove 63 may be any of rectangular, semi-circular, triangular, etc., a rectangular shape is most preferable. The width B of the groove is preferably 0.1 mm to 0.55 mm, the depth h is approximately 3 times the width B.

It should be understood from the foregoing description that since the oil seal of the present invention is a simple structure, it may be used for maintaining the proper oil seal action for a long time.

What is claimed is:

1. In an oil seal for use with a rotary piston internal combustion engine, said oil seal including an annular sliding face on an axial out side thereof formed into a lip face disposed at a lip angle a to an adjacent inside wall face of a side housing of the engine with the radial inner peripheral side of the sliding face constituting an annular contacting face disposed in frictional sliding contact with said inside wall face, the improvement comprising an annular groove in said sliding surface of said oil seal in such a position that only at least a portion of the area between the radially inner peripheries of the groove and oil seal contact the inside wall face of the side housing, the distance between the radially inner peripheral faces of the groove and the oil seal is no larger than 0.8 mm, the width of the groove is be tween 0.1 mm and 0.55 mm and the depth of the groove is 3 times the groove width. 

1. In an oil seal for use with a rotary piston internal combustion engine, said oil seal including an annular sliding face on an axial out side thereof formed into a lip face disposed at a lip angle Alpha to an adjacent inside wall face of a side housing of the engine with the radial inner peripheral side of the sliding face constituting an annular contacting face disposed in frictional sliding contact with said inside wall face, the improvement comprising an annular groove in said sliding surface of said oil seal in such a position that only at least a portion of the area between the radially inner peripheries of the groove and oil seal contact the inside wall face of the side housing, the distance between the radially inner peripheral faces of the groove and the oil seal is no larger than 0.8 mm, the width of the groove is between 0.1 mm and 0.55 mm and the depth of the groove is 3 times the groove width. 